Study on Abiding Efficiecy of Cypermethrin and Bacillus Thuringensis Mixture Insecficide to Culex pipiens quinque facciatus in laboratory

Objective: To study on the mixture insecticide efficacy against Culex pipiens quinquefaciatus larva. Method: Determining the LC 50 . Result: Cypermethrin and Bacillus thuringensis mixture insecticide to sensitive Culex pipiens quinguefaciatus larva LC 50 was 0.005 6 mg/L, the guotiety was 0.98 , which to resistant Culex pipiens quinquefaciatus larva LC 50 was 0.054 5 mg/L, the toxicity quotiety was 284.03 ,they have obvious synergistic action. Concoulion:On the dosage of 2.5 mg/L consistancy to sensitive and resistant type,the killing efficiency was over 80% in the laboratory and validity time was 21 days. The efficiency quotiety was longer than that with 0.5 mg/L Cypermethrin and 2.0 mg/L B.t.i.H-14. But after 21 days, mixture insecticide efficiency quickly decreased. One month later, it was out of action.